Mobile communication devices, typically portable telephone terminals, have in recent years been undergoing efforts to make themselves compatible with HSPA (High Speed Packet Access) for high-speed packet communications. Efforts have also been made to realize mobile communication networks for higher communication speeds by introducing LTE (Long Term Evolution) for packet communications higher in speed than HSPA. In order to introduce a new communication process, it is necessary to construct a network infrastructure compatible with the new communication process. However, it is difficult to replace existing facilities all at once with those of the new network infrastructure. While the new communication process is being introduced, therefore, a situation occurs wherein both the new communication process and the existing communication process exist together.
Generally, mobile communication devices are unable to communicate with each other unless terminals and base stations operate according to compatible communication processes. Consequently, a terminal which is not compatible with the new communication process cannot communicate in an area that includes a base station that operates based on the new communication process, and hence cannot benefit from the new communication process. Conversely, during a transient period wherein the number of base station areas that operate according to the new communication process is expanding, terminals which are compatible with only the new communication process that is capable of high-speed communication may be used in limited areas compared with terminals according to the old communication processes.
FIG. 1 is a diagram showing by way of example a wireless communication environment involving a plurality of coexisting communication processes.
For handling the above situation in a wireless communications environment involving a plurality of coexisting communication processes such as GPRS (General Packet Radio Service), WCDMA (Wideband Code Division Multiple Access), HSPA, LTE, etc., as shown in FIG. 1, research has been conducted on a technology (multimode) for performing data communications such as electronic mail, Internet access, etc. A technology called multimode LTE is compatible with a plurality of communication processes including third-generation WCDMA, GPRS, etc. as well as LTE. For example, a terminal compatible with an LTE/WCDMA multimode can communicate according to the LTE communication process when in an LTE base station area, and can communicate according to the WCDMA communication process when moved to a WCDMA base station area.
Relevant technologies applicable to a wireless communication environment that includes a plurality of coexisting communication processes are disclosed in Patent documents 1, 2.
According to Patent document 1, there is disclosed a technology for avoiding a reduction in the throughput due to biased reliance on a certain communication process in a wireless communication environment involving a plurality of coexisting different communication processes which are independent of each other.
According to Patent document 2, there is disclosed a technology which is free of a compressing or terminating mechanism in an exchange center (or a service node) as a compression process for making a transmission bandwidth more efficient. According to the disclosed technology, instead, a compressing or terminating mechanism is provided in a wireless network controller to thereby process protocol data packets.